Synthesis of 1,2,3-Triazole-Fused Indole Derivatives via Copper-Catalyzed Cascade Reaction

Article abstract of DOI:10.1055/a-1364-9308

A copper-catalyzed tandem reaction has been developed for the synthesis of 1,2,3-triazole-fused indole derivatives. This protocol allowed us to access a wide range of 1,2,3-triazole-fused indole derivatives in moderate to excellent yields. The 1,2,3-triazole-fused indole derivatives emit blue and greenish light when excited at 365 nm. The products were further explored for their quantum efficiency and photophysical properties.

Full text of DOI:10.1055/a-1364-9308

SYNTHESIS
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart
2021, 53, A–K
paper
A
en
K. Majeed et al.
Paper
Synthesis
Synthesis of 1,2,3-Triazole-Fused Indole Derivatives via Copper-
Catalyzed Cascade Reaction
Kashif Majeeda
Bangjie Liua
R
R
N
Fengtao Zhou*b
Qiuyu Zhang*a
CuAAC
NaN3, CuI, Na2CO3
N
N
X
DMSO, 95 °C
a Xi’an Key Laboratory of Functional Organic Porous Materials,
Department of Applied Chemistry, School of Chemistry and
Chemical Engineering, Northwestern Polytechnical University,
Xi’an, Shaanxi 710072, P. R. of China
70–96%
27 examples
qyzhang@nwpu.edu.cn
b School of Pharmacy, Jinan University, Guangzhou, Guangdong
510632, P. R. of China
fengtaozhou@163.com
Corresponding Authors
Received: 29.12.2020
Accepted after revision: 19.01.2021
Published online: 19.01.2021
O NC
O
CN
HN
N
N
N
HO
DOI: 10.1055/a-1364-9308; Art ID: ss-2020-g0667-op
Abstract A copper-catalyzed tandem reaction has been developed
for the synthesis of 1,2,3-triazole-fused indole derivatives. This protocol
allowed us to access a wide range of 1,2,3-triazole-fused indole deriva-
tives in moderate to excellent yields. The 1,2,3-triazole-fused indole de-
rivatives emit blue and greenish light when excited at 365 nm. The
products were further explored for their quantum efficiency and photo-
physical properties.
Prioline
Antitumor agent
Chiral diamine
N
N
N
CN
S
N
NH2
N
H
N
B
F
F
This work
O
F
HN
Kinase inhibitor
Key words 1,2,3-triazole-fused indoles, [3+2] cycloaddition, C–N
Fluorescent dye
bond formation, tandem reaction, sodium azide
Figure 1 Benzo[cd]indole-based molecules having different biological
activities
Nitrogen-containing heterocycles represent a highly im-
portant class of compounds which are widely used in medi-
cine, functional materials, and fine chemicals because of
their unique physical and chemical properties.1 These mo-
tifs have been considered as ‘privileged structures’ in me-
dicinal and synthetic organic chemistry because of their
promising features and pharmacological behavior. They
serve as key building blocks and intermediates in the design
and synthesis of numerous pharmaceuticals, and act as lead
compounds in the drug development field by facilitating bi-
ological investigations.2 Benzo[cd]indoles have been report-
ed for their potential in the development of diverse bioac-
tive compounds and chemotherapeutic agents, including
those with antiviral, antifungal, anti-tubulin, antihyperten-
sive, antimicrobial, antiproliferative, anti-inflammatory, an-
algesic, and antitumor activities3a,d,4b (Figure 1).
one derivatives. These are based on a sequential Stille cou-
pling and proline-catalyzed cyclization/aromatization pro-
cedure and a Pd/Cu-catalyzed C–H bond functionaliza-
tion/carbonylation process, respectively.5a,b In addition, a
quite recent study has reported silver-catalyzed stereose-
lective synthesis of 1,2-dihydrobenzo[cd]indole derivatives
from 8-ethynyl-1-naphthylamines.5a Another similar study
has reported palladium/iodine-cocatalyzed synthesis of
1,2-dihydrobenzo[cd]indole derivatives from 8-ethynyl-1-
naphthylamines (Scheme 1).5d Thus, it still remains a great
challenging task to develop an efficient and general syn-
thetic approach to construct 1,2-dihydrobenzo[cd]indoles
and their derivatives. However, to our knowledge, no syn-
thetic approach towards the synthesis of benzo[cd]-
[1,2,3]triazolo[1,5-a]indole derivatives has been reported.
Based on our previous work on sodium azide and peri-
substituted naphthalenes,6 we conceived that a copper-cat-
alyzed tandem approach would be the best strategy to get
triazole-fused indole derivatives 2 from 1-halo-8-(aryl-
ethynyl)naphthalenes 1 and sodium azide (Scheme 2).
Therefore, to confirm the feasibility of this proposed route
However, only few methods are available for the synthe-
sis of 1,2-dihydrobenzo[cd]indoles. These traditional meth-
ods use benzo[cd]indol-2(1H)-ones as intermediates, which
can be prepared from 1H,3H-benzo[de]isochromene-1,3-di-
ones (Scheme 1).3a,d,4b Lately, two newly discovered strate-
gies were also employed to access benzo[cd]indol-2(1H)-
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Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B
K. Majeed et al.
Paper
Synthesis
this transformation, as no product 2a was formed at room
temperature (entries 12 and 13). Eventually, the optimized
reaction conditions were identified: 1-iodo-8-(phenyl-
ethynyl)naphthalene (1a, 1.0 equiv), NaN3 (1.5 equiv), CuI
(5.0 mol%), Na2CO3 (2.0 equiv), DMSO (2 mL), 95 °C, in a
closed vessel.
R2
R1
NH
O
O
O
R
R1
N
R
refs. 3a,d; ref 4b
Table 1 Optimization of the Reaction Conditionsa
R2
R1
N
O
N
N
R2
I
CuI, Na2CO3
solvent, temp
O
ref. 5b
N
N
NaN3
R1
ref. 5a
R2
1a
2a
Temp (°C) Yield (%) 2ab
Scheme 1 Published approaches to benzo[cd]indole derivatives
Entry Base
CuI (mol%) Solvent
R
R
R
1
2
–
–
–
–
–
–
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMF
95
95
95
95
95
95
95
95
95
95
95
rt
26d
60f
78c
84d
91e
96
N
X
–
N3
N
[Cu], NaN3
N
[3+2] AAC
3
5.0
5.0
5.0
5.0
2.5
5.0
5.0
5.0
5.0
5.0
5.0
4
1
2
5
intermediate A
6
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Scheme 2 Proposed route for the CuAAC reaction of 1-halo-8-(aryl-
ethynyl)naphthalenes with sodium azide
7
64
8
89
as illustrated in Scheme 2, we began to explore the practi-
cality of this transformation.
9
1,4-dioxane
MeCN
40
10
11
12
13
54
To explore the reaction conditions, we chose sodium
azide and 1-iodo-8-(phenylethynyl)naphthalene (1a) as our
model substrates, and the results are summarized in Table
1. Firstly, the reaction was conducted in DMSO at 95 °C in a
closed vessel and desired cyclized product 2a was obtained
in 26% yield after 24 hours (entry 1). Inspired by this amaz-
ing discovery, various reaction parameters such as solvent,
temperature, and equivalents of sodium azide were then
optimized to further improve the yield. At first, we used 3.0
equivalents of sodium azide, and this significantly im-
proved the reaction yield to 60% (entry 2). However, in-
creasing the equivalents of sodium azide further did not
improve the yield. Next, the reaction was carried out in the
presence of CuI (5.0 mol%) as catalyst. To our delight, the
desired product 2a was successfully isolated in 91% yield
(entry 5), indicating that the copper catalyst plays an im-
portant role in the reaction process. To reduce the amount
of sodium azide, we used Na2CO3 as base in this transforma-
tion. Luckily, the desired product 2a was isolated in 96%
yield (entry 6). Reducing the catalyst loading greatly affect-
ed the reaction yield (entry 7). Next, this transformation
was also performed in different solvents, and DMSO proved
to be the most effective solvent (entries 8–11). Decreasing
the temperature of the reaction led to the reduction of
product yield, suggesting high temperature is crucial for
toluene
DMSO
DMSO
n.d.g
n.d.g
68
60
a Reaction conditions: 1a (0.2 mmol, 1.0 equiv), NaN3 (0.3 mmol, 1.5 equiv),
CuI (5.0 mol%), Na2CO3 (0.4 mmol, 2.0 equiv), solvent (2.0 mL).
b Isolated yields.
c NaN3 (0.3 mmol, 1.5 equiv).
d NaN3 (0.4 mmol, 2.0 equiv).
e NaN3 (0.5 mmol, 2.5 equiv).
f NaN3 (0.6 mmol, 3.0 equiv).
g No desired product was detected.
With the optimized conditions in hand, we then investi-
gated the scope of this tandem reaction, and the results are
shown in Scheme 3. Various substrates 1 were efficiently
prepared by the Sonogashira cross-coupling reaction. Al-
most all the substrates showed great tolerance to this trans-
formation, thereby affording the corresponding products
2a–2t in high yields. All reactions proceeded smoothly un-
der standard conditions and were completed within 8–12
hours. The aryl substituents such as a phenyl group or
phenyl group substituted with an electron-donating group
(-Me, -Et, -n-Pr, -OMe, -OEt) or an electron-withdrawing
group (-F, -Cl, -Br, -CO2Me) on the alkyne moiety of naph-
thalene 1 showed great feasibility to the reaction and the
corresponding products were obtained in yields of 78–96%
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–K

C
K. Majeed et al.
Paper
Synthesis
R
R
NaN3
N
X
CuI (5 mol%), Na2CO3
N
N
DMSO, 95 °C
1
2
X = I, R = alkyl, aryl, heteroaryl
Me
Et
n-Pr
MeO
EtO
Me
F
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
2a, 96%
2b, 84%
2c, 81%
2d, 85%
2e, 79%
2f, 81%
2g, 78%
2h, 72%
F
Cl
Br
MeO2C
F
N
OBn
Cl
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
2i, 73%
2j, 79%
2k, 89%
2l, 87%
2m, 90%
2n, 70%
2o, 87%
2p, 89%
S
N
N
N
N
N
N
N
N
N
N
N
N
2q, 78%
2r, 82%
2s, 73%
2t, 76%
Scheme 3 Reaction scope. Reagents and conditions: 1 (0.4 mmol, 1.0 equiv), NaN3 (0.6 mmol, 1.5 equiv), CuI (5.0 mol%), Na2CO3 (0.8 mmol, 2.0
equiv), DMSO (4.0 mL), 95 °C, 8–12 h; isolated yields.
R
(2a–2g) and 70–90% (2h–2n), respectively. Heterocycles
such as pyridine and thiophene, as well as polycyclic aro-
matic rings such as naphthalene, also showed great feasibil-
R
NaN3
N
X
CuI (5 mol%), Na2CO3
N
N
DMSO, 95 °C
ity to this reaction and gave 89%, 78%, and 82% yield of the
corresponding products (2p–2r). Alkyl substituents on the
1
2
alkyne moiety were also well tolerated and the correspond-
ing products 2s and 2t were delivered in 73% and 76% yield,
respectively. Finally, to our delight, other less reactive aryl
bromide substrates, 1aa–1ag, were also well tolerated, de-
livering 2a, 2k, 2l, 2p, 2r, 2ad, and 2af in high yields
(Scheme 4).
To demonstrate the utility of this copper-catalyzed
[3+2]-cycloaddition reaction, two scale-up experiments
were also conducted. The corresponding products 2f and 2l
were obtained with little decrease in isolated yields
(Scheme 5).
X = Br R = aryl, heteroaryl
F3C
R = C6H5,
2a, 85%
S
N
R = 4-FC6H4, 2k, 81%
R = 4-ClC6H4, 2l, 84%
R = 3-pyridyl, 2p, 83%
R = 2-naphthyl, 2r, 80%
N
N
N
N
N
2ad, 92%
2af, 87%
Scheme 4 Reaction scope. Reagents and conditions: 1 (0.4 mmol, 1.0
equiv), NaN3 (0.6 mmol, 1.5 equiv), CuI (5.0 mol%), Na2CO3 (0.8 mmol,
2.0 equiv), DMSO (4.0 mL), 95 °C, 8–12 h; isolated yields.
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–K

D
K. Majeed et al.
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Synthesis
OMe
MeO
N
I
N
NaN3, CuI, Na2CO3
N
DMSO, 95 °C
80%
1f, 1 g
Cl
2f, 0.623 g
Cl
N
Br
NaN3, CuI, Na2CO3
N
N
DMSO, 95 °C
82%
1ac, 1 g
2l, 0.741 g
Scheme 5 Gram-scale experiments
On the basis of the experimental observations and pre-
vious reports,7 the reaction pathway is consistent with our
proposed mechanism in Scheme 2. The reaction between 1-
halo-8-(arylethynyl)naphthalenes 1 and sodium azide pro-
ceeds by a two-step process for the synthesis of 1,2,3-tri-
azole-fused indole derivatives. In the first step, azido–
alkyne intermediate A is formed through a copper-cata-
lyzed azidation reaction which is a key step in this transfor-
mation and usually carried out at a relatively high tempera-
ture in DMSO. The subsequent step involves a formal [3+2]-
cycloaddition process and gives the final triazole-fused in-
dole product 2.
Finally, we studied the photophysical properties of 10
different compounds. As seen in Figure 2, these triazole-
fused indole products emitted blue and greenish light when
excited at 365 nm. The optical properties were measured
by UV-VIS and fluorescence spectroscopy in ethyl acetate.
Compound 2a will be considered the model compound
which will be compared to compounds with different elec-
tron-donating substituents (-Et, -OMe, -OEt) or electron-
withdrawing substituents (-F, -Cl, -CF3) on the phenyl ring.
Absorption and emission spectra for each compound are
shown in Figure 3.
Figure 3 Absorption spectra of various triazole-fused indole derivatives
(top) and fluorescence emission spectra (bottom) recorded in ethyl ace-
tate at room temperature
All the compounds have –* absorption bands in the
range of 300–450 nm. These values depend on the phenyl
ring and its electron-donating substituent. For instance,
compound 2a has no substituent, and the maximum ab-
sorption occurs at 377 nm. Compounds with an electron-
donating substituent, such as 2d, 2f, and 2g, have maxi-
mum absorption at 382, 389, and 390 nm, respectively, and
showed little effect on optical properties. Very little change
was observed in the absorption spectrum when an elec-
tron-withdrawing substituent was introduced, such as 2k,
2l, and 2ad. However, compound 2s with an n-butyl group
instead of a phenyl ring gave maximum absorption at 349
nm. This showed that the presence of a phenyl ring strongly
influences the optical properties of the products. The quan-
tum efficiency data of triazole-fused indole derivatives is
summarized in Table 2.
Figure 2 Fluorescence of 10 selected triazole-fused indole products
(1 mg/mL in EtOAc) under a 365 nm UV lamp
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Synthesis
Table 2 Quantum Efficiency of Triazole-Fused Indole Derivatives
1-Iodo-8-(phenylethynyl)naphthalene (1a); Typical Procedure for
Iodo Substrates 1
Compound abs max (nm)a em max (nm)b Δstokes
Φd
E
g (eV)e
To a solution of 1,8-diiodonaphthalene (760 mg, 2.0 mmol), PPh3 (13
mg, 0.05 mmol), and PdCl2(PPh3)2 (70 mg, 0.1 mmol) in Et3N (15.0
mL), phenylacetylene (0.23 mL, 1.05 equiv) was added, and the mix-
ture was stirred for 10 min at room temperature. After that time, CuI
(10 mg, 0.05 mmol) was added in one portion to the reaction mixture,
and the resulting brown suspension was then stirred at 50 °C for 12 h.
The reaction mixture was then diluted with diethyl ether and the re-
sulting dark solution was filtered through a pad of silica gel. The fil-
trate was concentrated under vacuum and purified via flash column
chromatography on silica gel (n-hexane) to afford 1a.
(nm)c
2a
2d
2f
377
382
389
390
377
378
374
373
386
349
440
468
472
468
448
430
438
428
430
418
63
86
83
78
71
52
64
55
44
69
0.00088
3.29
3.25
3.19
3.18
3.29
3.28
3.32
3.32
3.21
3.55
0.001
0.0015
0.0015
0.00098
0.00068
0.00087
0.00039
0.00049
0.0028
2g
2k
2l
Brown oil; yield: 51% (0.359 g).
2ad
2p
2r
1H NMR (400 MHz, CDCl3):  = 8.31 (dd, J = 7.2, 1.2 Hz, 1 H), 7.93 (dd,
J = 7.2, 1.2 Hz, 1 H), 7.84 (dd, J = 8.4, 1.2 Hz, 1 H), 7.81 (dd, J = 8.4, 1.2
Hz, 1 H), 7.69–7.64 (m, 2 H), 7.45–7.33 (m, 4 H), 7.11 (t, J = 7.6 Hz, 1
H).
2s
13C{1H} NMR (101 MHz, CDCl3):  = 142.7, 136.0, 134.9, 131.9, 130.8,
130.4, 130.2, 128.5, 128.4, 127.1, 125.5, 124.0, 122.8, 100.8, 92.9, 89.2.
HRMS (ESI): m/z [M + H]+ calcd for C18H11I: 354.9978; found:
354.9979.
a Excitation wavelength.
b Emission wavelength.
c Stokes shift, computed as Δ = em max – abs max
.
d Fluorescence quantum yield (Φ) was calculated based on 9,10-diphenyl-
anthracene (Φem = 0.95 in EtOH) at room temperature (see the Supporting
Information).
e Band gap calculated from onset of absorption spectra.
1-Iodo-8-(p-tolylethynyl)naphthalene (1b)
Brown oil; yield: 47% (0.347 g).
In summary, we successfully developed an efficient
method for the synthesis of various 1,2,3-triazole-fused tet-
racyclic heterocycles. The reaction proceeds smoothly un-
der standard conditions via a formal [3+2]-cycloaddition
cascade reaction to afford the corresponding products in
excellent yields. Easily available starting materials, mild re-
action conditions, and great functional group tolerance are
some core features of this novel protocol. We believe that
this study will lay the foundations for many other useful
transformations both in medicinal chemistry and organic
synthesis in the near future. Further research and applica-
tions of this newly discovered strategy for the synthesis of
other structurally novel triazole-fused heterocyclic com-
pounds is currently underway in our laboratory.
1H NMR (400 MHz, CDCl3):  = 8.30 (dd, J = 7.2, 1.2 Hz, 1 H), 7.92 (dd,
J = 7.2, 1.2 Hz, 1 H), 7.83 (dd, J = 8.0, 1.2 Hz, 1 H), 7.80 (dd, J = 8.0, 1.2
Hz, 1 H), 7.57 (d, J = 8.0 Hz, 2 H), 7.44 (t, J = 7.2 Hz, 1 H), 7.21 (d, J = 8.0
Hz, 2 H), 7.10 (t, J = 7.2 Hz, 1 H), 2.40 (s, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 142.7, 138.6, 135.8, 134.9, 131.9,
130.7, 130.2, 130.2, 129.3, 127.1, 125.5, 123.0, 121.0, 101.1, 93.0, 88.6,
21.6.
HRMS (ESI): m/z [M + H]+ calcd for C19H13I: 369.0135; found:
369.0127.
1-Iodo-8-(m-tolylethynyl)naphthalene (1c)
Brown oil; yield: 42% (0.313 g).
1H NMR (400 MHz, CDCl3):  = 8.32 (dd, J = 7.4, 1.3 Hz, 1 H), 7.94 (dd,
J = 7.2, 1.4 Hz, 1 H), 7.87–7.72 (m, 2 H), 7.56–7.48 (m, 2 H), 7.44 (t, J =
7.7 Hz, 1 H), 7.36–7.28 (m, 1 H), 7.25–7.19 (m, 1 H), 7.10 (t, J = 7.7 Hz,
1 H), 2.41 (s, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 142.4, 137.9, 135.7, 134.7, 131.6,
131.1, 130.1, 129.9, 129.2, 128.2, 127.8, 126.9, 125.3, 123.6, 122.7,
100.8, 92.8, 88.7, 21.2.
HRMS (ESI): m/z [M + H]+ calcd for C19H13I: 369.0135; found:
369.0132.
Unless otherwise noted, all reagents and materials were purchased
from commercial suppliers and used without further purification. All
new compounds were fully characterized by mass spectrometry and
NMR spectroscopy. Column chromatography was carried out using
silica gel (200–300 mesh). TLC analysis was performed using precoat-
ed silica gel glass plates and visualization of spots was by detection
under UV light (254 nm/365 nm). High-resolution mass spectra were
recorded with a WATERS -I Class VION IMS QTof electrospray mass
1-((4-Ethylphenyl)ethynyl)-8-iodonaphthalene (1d)
Brown oil; yield: 48% (0.379 g).
1
spectrometer. H NMR spectra were collected on Bruker Avance 400
1H NMR (400 MHz, CDCl3):  = 8.36–8.31 (m, 1 H), 7.99–7.92 (m, 1 H),
7.87–7.79 (m, 2 H), 7.64 (d, J = 8.0 Hz, 2 H), 7.46 (t, J = 7.7 Hz, 1 H),
7.27 (d, J = 8.0 Hz, 2 H), 7.12 (t, J = 7.7 Hz, 1 H), 2.73 (q, J = 7.6 Hz, 2 H),
1.31 (t, J = 7.6 Hz, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 144.6, 142.4, 135.6, 134.7, 131.6,
130.6, 130.0, 129.9, 127.8, 126.8, 125.2, 122.8, 121.0, 100.9, 92.1, 88.4,
28.7, 15.2.
MHz NMR spectrometers in CDCl3, and resonances () are given in
parts per million (ppm) relative to tetramethylsilane (internal stan-
dard). NMR data are reported as follows: chemical shift, multiplicity
(s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet), cou-
pling constant(s) J (Hz), and integration. 13C NMR spectra were re-
corded on Bruker Avance 100 MHz NMR spectrometers, in CDCl3, and
resonances () are given in ppm.
HRMS (ESI): m/z [M + H]+ calcd for C20H15I: 383.0291; found:
383.0290.
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K. Majeed et al.
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Synthesis
1-Iodo-8-((4-propylphenyl)ethynyl)naphthalene (1e)
HRMS (ESI): m/z [M + H]+ calcd for C18H10ICl: 388.9588; found:
388.9589.
Yellow oil; yield: 49% (0.389 g).
1H NMR (400 MHz, CDCl3):  = 8.31 (dd, J = 7.3, 1.3 Hz, 1 H), 7.93 (dd,
J = 7.2, 1.4 Hz, 1 H), 7.86–7.76 (m, 2 H), 7.63–7.56 (m, 2 H), 7.46–7.41
(m, 1 H), 7.23–7.19 (m, 2 H), 7.11–7.08 (m, 1 H), 2.68–2.56 (m, 2 H),
1.74–1.62 (m, 2 H), 0.97 (t, J = 7.3 Hz, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 143.1, 142.4, 135.6, 134.7, 131.6,
130.5, 130.0, 129.9, 128.4, 126.8, 125.3, 122.8, 121.0, 100.9, 92.8, 88.4,
37.8, 24.2, 13.6.
1-((3-Fluorophenyl)ethynyl)-8-iodonaphthalene (1j)
Yellow oil; yield: 52% (0.388 g).
1H NMR (400 MHz, CDCl3):  = 8.31 (dd, J = 7.4, 1.3 Hz, 1 H), 7.92 (dd,
J = 7.2, 1.4 Hz, 1 H), 7.86–7.78 (m, 2 H), 7.48–7.41 (m, 2 H), 7.41–7.32
(m, 2 H), 7.14–7.05 (m, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 162.3 (1JC-F = 245.0 Hz), 142.7,
136.0, 134.7, 131.7, 130.6, 130.0, 129.8 (3JC-F = 8.0 Hz), 127.0, 126.5
(4JC-F = 3.0 Hz), 125.6 (3JC-F = 9.0 Hz), 125.3, 122.1, 117.3 (2JC-F = 22.0
Hz), 115.5 (2JC-F = 21.0 Hz), 99.2 (4JC-F = 4.0 Hz), 92.7, 89.9.
HRMS (ESI): m/z [M + H]+ calcd for C21H17I: 397.0448; found:
397.0445.
1-Iodo-8-((4-methoxyphenyl)ethynyl)naphthalene (1f)
HRMS (ESI): m/z [M + H]+ calcd for C18H10FI: 372.9884; found:
372.9879.
Yellow solid; yield: 48% (0.367 g).
1H NMR (400 MHz, CDCl3):  = 8.30 (dd, J = 7.2, 1.2 Hz, 1 H), 7.90 (dd,
J = 7.2, 1.2 Hz, 1 H), 7.83 (dd, J = 8.0, 1.2 Hz, 1 H), 7.79 (dd, J = 8.0, 1.2
Hz, 1 H), 7.60 (d, J = 8.8 Hz, 2 H), 7.43 (t, J = 7.2 Hz, 1 H), 7.10 (t, J = 7.6
Hz, 1 H), 6.93 (d, J = 8.8 Hz, 2 H), 3.85 (s, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 159.8, 142.6, 135.6, 134.9, 132.3,
131.8, 130.2, 130.1, 127.1, 125.5, 123.1, 116.2, 114.1, 100.9, 93.0, 87.9,
55.4.
1-((4-Fluorophenyl)ethynyl)-8-iodonaphthalene (1k)
Off-white solid; yield: 61% (0.455 g).
1H NMR (400 MHz, CDCl3):  = 8.30 (dd, J = 7.3, 1.3 Hz, 1 H), 7.91 (dd,
J = 7.2, 1.4 Hz, 1 H), 7.86–7.77 (m, 2 H), 7.69–7.60 (m, 2 H), 7.46–7.41
(m, 1 H), 7.15–7.05 (m, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 162.5 (1JC-F = 248.0 Hz), 142.5,
135.8, 134.7, 132.4 (3JC-F = 9.0 Hz), 131.7, 130.3, 130.0, 126.9, 125.3,
122.4, 119.9 (4JC-F = 3.0 Hz), 115.6 (2JC-F = 22.0 Hz), 99.5, 92.7, 88.7
(4JC-F = 2.0 Hz).
HRMS (ESI): m/z [M + H]+ calcd for C19H13IO: 385.0084; found:
385.0078.
1-((4-Ethoxyphenyl)ethynyl)-8-iodonaphthalene (1g)
HRMS (ESI): m/z [M + H]+ calcd for C18H10FI: 372.9884; found:
372.9886.
Brown solid; yield: 45% (0.361 g).
1H NMR (400 MHz, CDCl3):  = 8.30 (dd, J = 7.2, 1.2 Hz, 1 H), 7.90 (dd,
J = 7.2, 1.2 Hz, 1 H), 7.83 (dd, J = 8.0, 1.2 Hz, 1 H), 7.79 (dd, J = 8.0, 1.2
Hz, 1 H), 7.59 (d, J = 8.8 Hz, 2 H), 7.43 (t, J = 7.6 Hz, 1 H), 7.10 (t, J = 7.6
Hz, 1 H), 6.91 (d, J = 8.8 Hz, 2 H), 4.07 (q, J = 7.2 Hz, 2 H), 1.44 (t, J = 7.2
Hz, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 159.2, 142.6, 135.6, 134.9, 132.3,
131.8, 130.2, 130.0, 127.1, 125.5, 123.2, 116.0, 114.6, 101.0, 93.0, 87.9,
63.6, 14.8.
1-((4-Chlorophenyl)ethynyl)-8-iodonaphthalene (1l)
Light brown solid; yield: 54% (0.420 g).
1H NMR (400 MHz, CDCl3):  = 8.30 (dd, J = 7.4, 1.2 Hz, 1 H), 7.91 (dd,
J = 7.3, 1.3 Hz, 1 H), 7.86–7.77 (m, 2 H), 7.62–7.55 (m, 2 H), 7.43 (t, J =
7.7 Hz, 1 H), 7.40–7.34 (m, 2 H), 7.10 (t, J = 7.7 Hz, 1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 142.6, 135.9, 134.7, 134.2, 131.8,
131.7, 130.5, 130.0, 128.6, 127.0, 125.3, 122.3, 122.3, 99.4, 92.6, 90.0.
HRMS (ESI): m/z [M + H]+ calcd for C20H15IO: 399.0241; found:
399.0233.
HRMS (ESI): m/z [M + H]+ calcd for C18H10ICl: 388.9588; found:
388.9581.
1-((2-Fluorophenyl)ethynyl)-8-iodonaphthalene (1h)
1-((4-Bromophenyl)ethynyl)-8-iodonaphthalene (1m)
Dark brown oil; yield: 44% (0.330 g).
Off-white solid; yield: 46% (0.396 g).
1H NMR (400 MHz, CDCl3):  = 8.30 (dd, J = 7.4, 1.3 Hz, 1 H), 7.97 (dd,
J = 7.3, 1.4 Hz, 1 H), 7.87–7.80 (m, 2 H), 7.69 (td, J = 7.4, 1.8 Hz, 1 H),
7.48–7.44 (m, 1 H), 7.38–7.30 (m, 1 H), 7.20–7.09 (m, 3 H).
1H NMR (400 MHz, CDCl3):  = 8.31 (dd, J = 7.4, 1.3 Hz, 1 H), 7.92 (dd,
J = 7.3, 1.4 Hz, 1 H), 7.84 (td, J = 8.1, 1.3 Hz, 2 H), 7.55–7.48 (m, 4 H),
7.47–7.43 (m, 1 H), 7.14–7.10 (m, 1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 162.5 (1JC-F = 250.0 Hz), 142.5,
136.3, 134.7, 132.3 (4JC-F = 2.0 Hz), 131.7, 130.6, 130.0, 129.8 (3JC-F = 8.0
Hz), 127.0, 125.3, 123.9 (4JC-F = 3.0 Hz), 122.3, 115.5 (2JC-F = 21.0 Hz),
112.5 (2JC-F = 25.0 Hz), 94.5, 93.8 (4JC-F = 3.0 Hz), 92.8.
13C{1H} NMR (101 MHz, CDCl3):  = 142.6, 135.9, 134.8, 132.1, 131.7,
131.6, 130.6, 130.1, 127.1, 125.3, 122.8, 122.5, 122.3, 99.5, 92.6, 90.2.
HRMS (ESI): m/z [M + H]+ calcd for C18H10IBr: 432.9083; found:
432.9084.
HRMS (ESI): m/z [M + H]+ calcd for C18H10FI: 372.9884; found:
372.9883.
Methyl 4-((8-Iodonaphthalen-1-yl)ethynyl)benzoate (1n)
Dark brown solid; yield: 50% (0.411 g).
1-((2-Chlorophenyl)ethynyl)-8-iodonaphthalene (1i)
1H NMR (400 MHz, CDCl3):  = 8.30 (d, J = 7.3 Hz, 1 H), 8.06 (d, J = 8.0
Hz, 2 H), 7.93 (d, J = 7.2 Hz, 1 H), 7.85–7.81 (m, 2 H), 7.71 (d, J = 8.1 Hz,
2 H), 7.45 (t, J = 7.7 Hz, 1 H), 7.11 (t, J = 7.7 Hz, 1 H), 3.94 (s, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 166.5, 142.6, 136.2, 134.7, 131.7,
130.8, 130.5, 130.1, 129.4, 129.3, 128.4, 127.1, 125.3, 122.05, 99.7,
92.6, 92.1, 52.1.
Off-white solid; yield: 52% (0.403 g).
1H NMR (400 MHz, CDCl3):  = 8.31 (dd, J = 7.3, 1.3 Hz, 1 H), 7.92 (dd,
J = 7.2, 1.4 Hz, 1 H), 7.87–7.79 (m, 2 H), 7.66–7.61 (m, 1 H), 7.57–7.51
(m, 1 H), 7.47–7.43 (m, 1 H), 7.38–7.29 (m, 2 H), 7.15–7.07 (m, 1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 142.6, 136.0, 134.7, 134.1, 131.7,
130.6, 130.4, 130.0, 129.5, 128.8, 128.5, 127.0, 125.5, 125.3, 122.1,
99.0, 92.7, 90.2.
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–K

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K. Majeed et al.
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Synthesis
HRMS (ESI): m/z [M + H]+ calcd for C20H13IO2: 413.0033; found:
1-(Hept-1-yn-1-yl)-8-iodonaphthalene (1t)
413.0036.
Dark brown oil; yield: 48% (0.334 g).
1H NMR (400 MHz, CDCl3):  = 8.27 (dd, J = 7.4, 1.3 Hz, 1 H), 7.84–7.70
(m, 3 H), 7.37 (t, J = 7.7 Hz, 1 H), 7.06 (t, J = 7.7 Hz, 1 H), 2.53 (t, J = 7.2
Hz, 2 H), 1.76–1.67 (m, 2 H), 1.54–1.46 (m, 2 H), 1.44–1.34 (m, 2 H),
0.94 (t, J = 7.3 Hz, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 142.4, 135.4, 134.7, 131.7, 129.9,
129.4, 126.7, 125.2, 123.3, 103.0, 92.7, 79.8, 31.3, 27.5, 22.2, 20.4,
13.9.
1-(3-(Benzyloxy)prop-1-yn-1-yl)-8-iodonaphthalene (1o)
Light orange solid; yield: 47% (0.396 g).
1H NMR (400 MHz, CDCl3):  = 8.32 (dd, J = 7.4, 1.3 Hz, 1 H), 7.89 (dd,
J = 7.2, 1.4 Hz, 1 H), 7.87–7.81 (m, 2 H), 7.49–7.39 (m, 5 H), 7.37–7.34
(m, 1 H), 7.12 (t, J = 7.7 Hz, 1 H), 4.80 (s, 2 H), 4.57 (s, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 142.6, 137.5, 136.2, 134.6, 131.8,
130.5, 130.0, 128.3, 128.3, 127.9, 127.7, 126.9, 125.2, 121.6, 97.3, 92.5,
85.7, 71.8, 58.8.
HRMS (ESI): m/z [M + H]+ calcd for C17H17I: 349.0448; found:
349.0457.
HRMS (ESI): m/z [M + Na]+ calcd for C20H15IO: 421.0060; found:
421.0061.
1-Bromo-8-(phenylethynyl)naphthalene (1aa); Typical Procedure
for Bromo Substrates 1
3-((8-Iodonaphthalen-1-yl)ethynyl)pyridine (1p)
To a solution of 1,8-dibromonaphthalene (572 mg, 2.0 mmol), PPh3
(13 mg, 0.05 mmol), and PdCl2(PPh3)2 (70 mg, 0.1 mmol) in Et3N (15.0
mL), phenylacetylene (0.23 mL, 1.05 equiv) was added, and the mix-
ture was stirred for 10 min at room temperature. After that time, CuI
(10 mg, 0.05 mmol) was added in one portion to the reaction mixture,
and the resulting brown suspension was then stirred at 70 °C for 12 h.
The reaction mixture was then diluted with diethyl ether and the re-
sulting dark solution was filtered through a pad of silica gel. The fil-
trate was concentrated under vacuum and purified via flash column
chromatography on silica gel (n-hexane) to afford 1aa.
Light brown solid; yield: 42% (0.299 g).
1H NMR (400 MHz, CDCl3):  = 8.91–8.86 (m, 1 H), 8.58 (dd, J = 4.9, 1.7
Hz, 1 H), 8.31 (dd, J = 7.4, 1.3 Hz, 1 H), 7.96–7.90 (m, 2 H), 7.87–7.82
(m, 2 H), 7.48–7.44 (m, 1 H), 7.35–7.29 (m, 1 H), 7.14–7.10 (m, 1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 151.4, 148.5, 142.7, 137.5, 136.1,
134.8, 131.7, 130.9, 130.1, 127.1, 125.3, 123.0, 121.9, 120.9, 97.2, 92.6,
92.3.
HRMS (ESI): m/z [M + H]+ calcd for C17H10IN: 355.9931; found:
355.9934.
Light yellow oil; yield: 50% (0.307 g).
1H NMR (400 MHz, CDCl3):  = 7.92 (dd, J = 7.3, 1.3 Hz, 1 H), 7.89 (dd,
J = 7.4, 1.3 Hz, 1 H), 7.84–7.77 (m, 2 H), 7.68–7.63 (m, 2 H), 7.49–7.37
(m, 4 H), 7.28 (t, J = 7.8 Hz, 1 H).
2-((8-Iodonaphthalen-1-yl)ethynyl)thiophene (1q)
Dark brown oil; yield: 45% (0.323 g).
1H NMR (400 MHz, CDCl3):  = 8.33 (dd, J = 7.4, 1.3 Hz, 1 H), 7.92 (dd,
J = 7.3, 1.4 Hz, 1 H), 7.88–7.79 (m, 2 H), 7.48–7.44 (m, 1 H), 7.42 (dd,
J = 3.7, 1.1 Hz, 1 H), 7.37 (dd, J = 5.1, 1.2 Hz, 1 H), 7.17–7.07 (m, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 135.6, 135.5, 133.8, 130.7, 130.4,
129.7, 129.0, 128.2, 128.1, 126.3, 125.5, 123.9, 120.8, 120.5, 97.5, 90.1.
HRMS (ESI): m/z [M + H]+ calcd for C18H11Br: 307.0117; found:
307.0119.
13C{1H} NMR (101 MHz, CDCl3):  = 142.5, 135.3, 134.7, 131.6, 130.8,
130.4, 130.0, 127.2, 126.9, 126.9, 125.3, 123.9, 122.2, 94.8, 92.9, 92.8.
HRMS (ESI): m/z [M + H]+ calcd for C16H9IS: 360.9542; found:
1-Bromo-8-((4-fluorophenyl)ethynyl)naphthalene (1ab)
360.9539.
White solid; yield: 54% (0.351 g).
1H NMR (400 MHz, CDCl3):  = 7.95–7.87 (m, 2 H), 7.87–7.78 (m, 2 H),
7.67–7.57 (m, 2 H), 7.49–7.45 (m, 1 H), 7.30 (t, J = 8.0 Hz, 1 H), 7.15–
7.05 (m, 2 H).
1-Iodo-8-(naphthalen-2-ylethynyl)naphthalene (1r)
Light brown solid; yield: 47% (0.381 g).
1H NMR (400 MHz, CDCl3):  = 8.33 (dd, J = 7.4, 1.3 Hz, 1 H), 8.19 (d, J =
1.5 Hz, 1 H), 7.99 (dd, J = 7.3, 1.4 Hz, 1 H), 7.89–7.80 (m, 5 H), 7.75 (dd,
J = 8.5, 1.6 Hz, 1 H), 7.54–7.50 (m, 2 H), 7.46 (t, J = 7.7 Hz, 1 H), 7.11 (t,
J = 7.7 Hz, 1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 162.4 (1JC-F = 247.0 Hz), 135.5 (4JC-F
=
4.0 Hz), 133.9, 132.6 (3JC-F = 8.0 Hz), 130.4, 129.8, 129.0, 126.3, 125.5,
120.5 (2JC-F = 21.0 Hz), 120.0 (4JC-F = 3.0 Hz), 115.6 (2JC-F = 22.0 Hz),
96.4, 89.8, 89.7.
13C{1H} NMR (101 MHz, CDCl3):  = 142.5, 135.9, 134.8, 132.9, 132.8,
131.8, 130.5, 130.3, 130.0, 127.9, 127.7, 127.6, 127.4, 126.9, 126.5,
126.4, 125.3, 122.7, 121.2, 101.1, 92.8, 89.4.
HRMS (ESI): m/z [M + H]+ calcd for C18H10BrF: 325.0023; found:
325.0031.
HRMS (ESI): m/z [M + H]+ calcd for C22H13I: 405.0135; found:
1-Bromo-8-((4-chlorophenyl)ethynyl)naphthalene (1ac)
405.0131.
White solid; yield: 59% (0.402 g).
1H NMR (400 MHz, CDCl3):  = 7.90–7.79 (m, 4 H), 7.54 (d, J = 8.1 Hz, 2
H), 7.45 (t, J = 7.7 Hz, 1 H), 7.36 (d, J = 8.1 Hz, 2 H), 7.29 (t, J = 8.4 Hz, 1
1-(Hex-1-yn-1-yl)-8-iodonaphthalene (1s)
Dark brown oil; yield: 47% (0.311 g).
H).
1H NMR (400 MHz, CDCl3):  = 8.27 (dd, J = 7.3, 1.3 Hz, 1 H), 7.82–7.71
(m, 3 H), 7.39–7.35 (m, 1 H), 7.06 (t, J = 7.7 Hz, 1 H), 2.54 (t, J = 7.1 Hz,
2 H), 1.74–1.64 (m, 2 H), 1.59–1.50 (m, 2 H), 0.98 (t, J = 7.3 Hz, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 135.7, 135.5, 134.1, 133.9, 131.9,
130.4, 129.9, 129.1, 128.6, 126.4, 125.5, 122.4, 120.5, 120.4, 96.3, 91.0.
HRMS (ESI): m/z [M + H]+ calcd for C18H10BrCl: 340.9727; found:
340.9699.
13C{1H} NMR (101 MHz, CDCl3):  = 142.4, 135.4, 134.7, 131.7, 129.9,
129.4, 126.7, 125.2, 123.3, 102.9, 92.7, 79.8, 29.9, 22.2, 20.2, 13.6.
HRMS (ESI): m/z [M + H]+ calcd for C16H15I: 335.0291; found:
335.0290.
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–K

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K. Majeed et al.
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Synthesis
1-Bromo-8-((4-(trifluoromethyl)phenyl)ethynyl)naphthalene
(1ad)
1H NMR (400 MHz, CDCl3):  = 8.13–8.04 (m, 2 H), 7.97 (d, J = 7.1 Hz, 1
H), 7.91 (d, J = 7.2 Hz, 1 H), 7.84 (d, J = 8.3 Hz, 1 H), 7.78 (d, J = 8.3 Hz,
1 H), 7.68–7.51 (m, 4 H), 7.49–7.39 (m, 1 H).
White solid; yield: 44% (0.327 g).
13C{1H} NMR (101 MHz, CDCl3):  = 140.5, 135.5, 132.4, 130.7, 130.5,
128.9, 128.9, 128.6, 128.5, 127.9, 127.3, 126.4, 125.7, 122.9, 121.7,
111.3.
HRMS (ESI): m/z [M + H]+ calcd for C18H11N3: 270.1026; found:
270.1021.
1H NMR (400 MHz, CDCl3):  = 7.93–7.87 (m, 2 H), 7.86–7.80 (m, 2 H),
7.70 (d, J = 8.1 Hz, 2 H), 7.64 (d, J = 8.3 Hz, 2 H), 7.48–7.44 (m, 1 H),
7.30 (t, J = 7.8 Hz, 1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 136.0, 135.5, 134.0, 130.9, 130.4,
130.4, 129.8 (2JC-F = 32.0 Hz), 129.1, 127.7, 126.5, 125.5, 125.2 (3JC-F
4.0 Hz), 123.9 (1JC-F = 270.0 Hz), 120.3, 120.0, 95.9, 92.5.
=
10-(p-Tolyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2b)
HRMS (ESI): m/z [M + H]+ calcd for C19H10BrF3: 374.9991; found:
Yellow solid; yield: 84% (96 mg).
374.9987.
1H NMR (400 MHz, CDCl3):  = 8.01–7.84 (m, 4 H), 7.78–7.73 (m, 2 H),
7.64–7.53 (m, 2 H), 7.35 (d, J = 7.7 Hz, 2 H), 2.44 (s, 3 H).
3-((8-Bromonaphthalen-1-yl)ethynyl)pyridine (1ae)
13C{1H} NMR (101 MHz, CDCl3):  = 140.5, 138.4, 135.2, 132.3, 130.6,
129.5, 128.8, 128.6, 127.8, 127.6, 127.1, 126.3, 125.6, 122.9, 121.5,
111.1, 21.3.
HRMS (ESI): m/z [M + H]+ calcd for C19H13N3: 284.1182; found:
284.1178.
Off-white solid; yield: 52% (0.321 g).
1H NMR (400 MHz, CDCl3):  = 8.84 (s, 1 H), 8.56 (d, J = 4.9 Hz, 1 H),
8.04–7.71 (m, 5 H), 7.46 (t, J = 7.7 Hz, 1 H), 7.38–7.27 (m, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 151.4, 148.4, 137.6, 135.9, 135.5,
134.0, 130.4, 130.4, 129.1, 126.5, 125.5, 123.0, 121.1, 120.3, 120.0,
94.0, 93.3.
10-(m-Tolyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2c)
HRMS (ESI): m/z [M + H]+ calcd for C17H10BrN: 308.0069; found:
Yellow solid; yield: 81% (92 mg).
308.0067.
1H NMR (400 MHz, CDCl3):  = 7.90–7.82 (m, 3 H), 7.80–7.72 (m, 2 H),
7.71 (d, J = 8.4 Hz, 1 H), 7.60–7.55 (m, 2 H), 7.45–7.38 (m, 1 H), 7.23
(d, J = 7.6 Hz, 1 H), 2.48 (s, 3 H).
3-((8-Bromonaphthalen-1-yl)ethynyl)thiophene (1af)
White solid; yield: 49% (0.309 g).
13C{1H} NMR (101 MHz, CDCl3):  = 140.5, 138.5, 135.4, 132.2, 130.5,
130.3, 129.2, 128.8, 128.6, 128.5, 127.7, 127.1, 127.0, 125.6, 123.4,
122.8, 121.5, 111.1, 21.4.
HRMS (ESI): m/z [M + H]+ calcd for C19H13N3: 284.1182; found:
284.1178.
1H NMR (400 MHz, CDCl3):  = 7.88 (td, J = 7.6, 1.3 Hz, 2 H), 7.81–7.78
(m, 2 H), 7.61 (dd, J = 3.0, 1.2 Hz, 1 H), 7.46–7.42 (m, 1 H), 7.35–7.27
(m, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 135.5, 135.3, 133.8, 130.4, 129.6,
129.0, 127.8, 126.3, 125.4, 125.3, 123.0, 120.6, 120.4, 93.1, 89.5.
HRMS (ESI): m/z [M + H]+ calcd for C16H9BrS: 312.9681; found:
312.9680.
10-(4-Ethylphenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2d)
Yellow solid; yield: 85% (100 mg).
1-Bromo-8-(naphthalen-2-ylethynyl)naphthalene (1ag)
1H NMR (400 MHz, CDCl3):  = 8.04–7.93 (m, 3 H), 7.94–7.87 (m, 1 H),
7.86–7.72 (m, 2 H), 7.67–7.56 (m, 2 H), 7.43–7.35 (m, 2 H), 2.75 (q, J =
7.6 Hz, 2 H), 1.32 (t, J = 7.6 Hz, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 144.8, 140.6, 135.3, 132.4, 130.7,
128.9, 128.7, 128.4, 127.9, 127.8, 127.1, 126.4, 125.6, 123.0, 121.5,
111.2, 28.7, 15.4.
White solid; yield: 51% (0.364 g).
1H NMR (400 MHz, CDCl3):  = 8.14 (d, J = 1.4 Hz, 1 H), 7.97 (dd, J = 7.3,
1.3 Hz, 1 H), 7.91 (dd, J = 7.5, 1.3 Hz, 1 H), 7.88–7.79 (m, 5 H), 7.70 (dd,
J = 8.5, 1.6 Hz, 1 H), 7.54–7.45 (m, 3 H), 7.30 (t, J = 7.8 Hz, 1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 135.7, 135.6, 133.9, 132.9, 132.7,
130.5, 129.8, 129.0, 128.3, 127.9, 127.7, 127.7, 127.5, 126.5, 126.4,
126.3, 125.5, 121.3, 120.8, 120.5, 97.9, 90.5.
HRMS (ESI): m/z [M + H]+ calcd for C20H15N3: 298.1339; found:
298.1332.
HRMS (ESI): m/z [M + H]+ calcd for C22H13Br: 357.0274; found:
357.0269.
10-(4-Propylphenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2e)
Yellow solid; yield: 79% (99 mg).
10-Phenylbenzo[cd][1,2,3]triazolo[1,5-a]indole (2a); Typical Pro-
cedure for Products 2
1H NMR (400 MHz, CDCl3):  = 7.99–7.93 (m, 2 H), 7.89 (d, J = 7.1 Hz, 1
H), 7.84 (d, J = 7.2 Hz, 1 H), 7.76 (d, J = 8.2 Hz, 1 H), 7.71 (d, J = 8.2 Hz,
1 H), 7.60–7.51 (m, 2 H), 7.39–7.32 (m, 2 H), 2.72–2.64 (m, 2 H), 1.77–
1.66 (m, 2 H), 1.00 (t, J = 7.3 Hz, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 143.2, 140.5, 135.1, 132.3, 130.5,
128.9, 128.9, 128.8, 128.5, 127.9, 127.7, 127.0, 126.3, 125.5, 122.9,
121.4, 111.1, 37.8, 24.3, 13.7.
A mixture of 1-iodo-8-(phenylethynyl)naphthalene (1a; 142.0 mg, 0.4
mmol), NaN3 (40.0 mg, 0.6 mmol), CuI (4.0 mg, 5.0 mol%), Na2CO3
(84.0 mg, 0.8 mmol), and DMSO (4.0 mL) in a closed vessel was stirred
for 8–12 hours at 95 °C. After disappearance of the reactant (moni-
tored by TLC), ammonia solution (2 mL) was added to the mixture,
which was then washed with water and extracted with DCM (3 × 25
mL). The combined extract was washed with brine, dried over anhy-
drous Na2SO4, and concentrated under reduced pressure. The residue
was purified by silica gel column chromatography (petroleum
ether/ethyl acetate, 3:1) to afford 2a.
HRMS (ESI): m/z [M + H]+ calcd for C21H17N3: 312.1495; found:
312.1492.
10-(4-Methoxyphenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2f)
Yellow solid; yield: 81% (98 mg).
Greenish solid; yield: 96% (102 mg).
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–K

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K. Majeed et al.
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1H NMR (400 MHz, CDCl3):  = 8.03–7.93 (m, 2 H), 7.93–7.82 (m, 2 H),
7.79–7.72 (m, 2 H), 7.61–7.55 (m, 2 H), 7.06 (d, J = 8.5 Hz, 2 H), 3.89 (s,
3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 159.7, 140.3, 134.7, 132.3, 130.6,
128.8, 128.6, 127.8, 127.7, 126.9, 125.5, 123.1, 123.0, 121.2, 114.2,
111.0, 55.2.
10-(4-Fluorophenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2k)
Greenish solid; yield: 89% (102 mg).
1H NMR (400 MHz, CDCl3):  = 8.05–7.98 (m, 2 H), 7.88 (d, J = 7.1 Hz, 2
H), 7.82 (d, J = 8.3 Hz, 1 H), 7.77 (d, J = 8.3 Hz, 1 H), 7.65–7.56 (m, 2 H),
7.26–7.18 (m, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 162.6 (1JC-F = 247.0 Hz), 139.5,
135.2, 132.3, 130.6, 128.8, 128.5, 128.1 (3JC-F = 8.0 Hz), 127.9, 127.4,
126.7 (4JC-F = 3.0 Hz), 125.8, 122.7, 121.4, 115.9 (2JC-F = 22.0 Hz), 111.3.
HRMS (ESI): m/z [M + H]+ calcd for C19H13N3O: 300.1131; found:
300.1125.
HRMS (ESI): m/z [M + H]+ calcd for C18H10FN3: 288.0932; found:
288.0928.
10-(4-Ethoxyphenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2g)
Yellow solid; yield: 78% (98 mg).
1H NMR (400 MHz, CDCl3):  = 8.04–7.99 (m, 2 H), 7.97 (d, J = 7.1 Hz, 1
H), 7.93 (d, J = 7.2 Hz, 1 H), 7.85 (d, J = 8.3 Hz, 1 H), 7.80 (d, J = 8.3 Hz,
1 H), 7.69–7.60 (m, 2 H), 7.11–7.04 (m, 2 H), 4.13 (q, J = 6.9 Hz, 2 H),
1.48 (t, J = 7.0 Hz, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 159.2, 140.5, 134.8, 132.5, 130.7,
128.9, 128.7, 127.9, 127.8, 127.0, 125.6, 123.2, 122.9, 121.3, 114.8,
111.2, 63.4, 14.7.
10-(4-Chlorophenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2l)
Greenish solid; yield: 87% (105 mg).
1H NMR (400 MHz, CDCl3):  = 8.03–7.96 (m, 2 H), 7.95–7.93 (m, 2 H),
7.88 (d, J = 8.3 Hz, 1 H), 7.81 (d, J = 8.3 Hz, 1 H), 7.71–7.59 (m, 2 H),
7.54–7.47 (m, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 139.4, 135.6, 134.2, 132.3, 130.7,
129.1, 129.0, 128.9, 128.6, 128.0, 127.6, 127.5, 125.9, 122.7, 121.7,
111.5.
HRMS (ESI): m/z [M + H]+ calcd for C20H15N3O: 314.1288; found:
314.1284.
HRMS (ESI): m/z [M + H]+ calcd for C18H10ClN3: 304.0636; found:
304.0632.
10-(2-Fluorophenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2h)
Brown solid; yield: 72% (82 mg).
10-(4-Bromophenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2m)
1H NMR (400 MHz, CDCl3):  = 8.21 (t, J = 7.6 Hz, 1 H), 7.93 (d, J = 7.2
Hz, 1 H), 7.90–7.85 (m, 1 H), 7.85–7.76 (m, 2 H), 7.67–7.56 (m, 2 H),
7.49–7.41 (m, 1 H), 7.35 (t, J = 7.6 Hz, 1 H), 7.32–7.26 (m, 1 H).
Brown solid; yield: 90% (126 mg).
1H NMR (400 MHz, CDCl3):  = 8.00–7.92 (m, 4 H), 7.90 (d, J = 8.3 Hz, 1
H), 7.84 (d, J = 8.3 Hz, 1 H), 7.72–7.63 (m, 4 H).
13C{1H} NMR (101 MHz, CDCl3):  = 139.6, 135.8, 132.5, 132.2, 130.9,
129.7, 129.1, 128.8, 128.2, 128.1, 127.8, 126.1, 122.9, 122.5, 122.0,
111.8.
13C{1H} NMR (101 MHz, CDCl3):  = 159.4 (1JC-F = 247.0 Hz), 137.1 (4JC-F
=
2.0 Hz), 133.8, 132.1, 130.4, 130.1 (3JC-F = 8.0 Hz), 129.6 (4JC-F = 3.0 Hz),
129.1 (4JC-F = 2.0 Hz), 128.5, 127.5, 127.1, 125.8, 124.6 (4JC-F = 3.0 Hz),
124.4, 124.2, 123.1, 118.9, 118.8, 115.6 (2JC-F = 21.0 Hz), 111.2.
HRMS (ESI): m/z [M + H]+ calcd for C18H10BrN3: 348.0131; found:
348.0127.
HRMS (ESI): m/z [M + H]+ calcd for C18H10FN3: 288.0932; found:
288.0928.
Methyl 4-(Benzo[cd][1,2,3]triazolo[1,5-a]indol-10-yl)benzoate
(2n)
10-(2-Chlorophenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2i)
Greenish solid; yield: 73% (89 mg).
Greenish solid; yield: 70% (91 mg).
1H NMR (400 MHz, CDCl3):  = 8.10 (t, J = 1.9 Hz, 1 H), 8.04 (d, J = 7.0
Hz, 1 H), 8.02–7.96 (m, 2 H), 7.93 (d, J = 8.3 Hz, 1 H), 7.86 (d, J = 8.3 Hz,
1 H), 7.75–7.65 (m, 2 H), 7.50 (t, J = 7.8 Hz, 1 H), 7.43–7.38 (m, 1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 139.2, 135.9, 134.9, 132.4, 132.4,
130.8, 130.2, 129.0, 128.7, 128.4, 128.1, 127.8, 126.5, 126.0, 124.5,
122.7, 122.0, 111.7.
1H NMR (400 MHz, CDCl3):  = 8.26–8.18 (m, 2 H), 8.17–8.11 (m, 2 H),
8.03 (d, J = 7.1 Hz, 1 H), 7.96 (d, J = 7.2 Hz, 1 H), 7.91 (d, J = 8.3 Hz, 1 H),
7.84 (d, J = 8.3 Hz, 1 H), 7.72–7.63 (m, 2 H), 3.97 (s, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 166.6, 139.4, 136.3, 134.9, 132.3,
130.7, 130.2, 129.7, 129.0, 128.6, 128.0, 127.9, 126.2, 126.1, 122.6,
122.2, 111.7, 52.1.
HRMS (ESI): m/z [M + H]+ calcd for C18H10ClN3: 304.0636; found:
304.0630.
HRMS (ESI): m/z [M + H]+ calcd for C20H13N3O2: 328.1081; found:
328.1079.
10-(3-Fluorophenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2j)
10-((Benzyloxy)methyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2o)
Greenish solid; yield: 79% (90 mg).
Light brown solid; yield: 87% (110 mg).
1H NMR (400 MHz, CDCl3):  = 8.02 (d, J = 7.1 Hz, 1 H), 7.97 (d, J = 7.2
Hz, 1 H), 7.90 (d, J = 8.3 Hz, 1 H), 7.88–7.82 (m, 2 H), 7.82–7.77 (m, 1
H), 7.72–7.64 (m, 2 H), 7.56–7.49 (m, 1 H), 7.16–7.10 (m, 1 H).
1H NMR (400 MHz, CDCl3):  = 7.92 (d, J = 7.2 Hz, 1 H), 7.85–7.80 (m, 2
H), 7.76 (d, J = 7.0 Hz, 1 H), 7.66–7.53 (m, 2 H), 7.44–7.29 (m, 5 H),
5.00 (s, 2 H), 4.72 (s, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 137.5, 132.8, 130.6, 129.0, 128.6,
128.3, 128.0, 127.8, 127.7, 127.0, 125.8, 123.2, 122.7, 111.3, 72.7, 64.4.
13C{1H} NMR (101 MHz, CDCl3):  = 163.1 (1JC-F = 244.0 Hz), 139.4 (4JC-F
=
3.0 Hz), 135.9, 132.7 (3JC-F = 8.0 Hz), 132.4, 130.7, 130.5 (3JC-F = 8.0 Hz),
128.9, 128.6, 128.0, 127.7, 125.9, 122.6, 122.1 (4JC-F = 3.0 Hz), 121.9,
115.3 (2JC-F = 23.0 Hz), 113.3 (2JC-F = 23.0 Hz), 111.6.
HRMS (ESI): m/z [M + Na]+ calcd for C20H15N3O: 336.1107; found:
336.1100.
HRMS (ESI): m/z [M + H]+ calcd for C18H10FN3: 288.0932; found:
288.0928.
10-(Pyridin-3-yl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2p)
Light brown solid; yield: 89% (96 mg).
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–K

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1H NMR (400 MHz, CDCl3):  = 9.27 (d, J = 2.3 Hz, 1 H), 8.72–8.61 (m, 1
H), 8.48–8.38 (m, 1 H), 8.01 (d, J = 7.1 Hz, 1 H), 7.95 (d, J = 7.2 Hz, 1 H),
7.88 (d, J = 8.3 Hz, 1 H), 7.82 (d, J = 8.3 Hz, 1 H), 7.72–7.61 (m, 2 H),
7.50–7.47 (m, 1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 149.4, 147.5, 137.2, 136.0, 133.5,
132.2, 130.7, 129.0, 128.5, 128.0, 127.8, 126.8, 126.1, 123.8, 122.4,
122.0, 111.7.
10-Phenylbenzo[cd][1,2,3]triazolo[1,5-a]indole (2a)
Greenish solid; yield: 85% (91 mg).
1H NMR (400 MHz, CDCl3):  = 8.13–8.04 (m, 2 H), 7.97 (d, J = 7.1 Hz, 1
H), 7.91 (d, J = 7.2 Hz, 1 H), 7.84 (d, J = 8.3 Hz, 1 H), 7.78 (d, J = 8.3 Hz,
1 H), 7.68–7.51 (m, 4 H), 7.49–7.39 (m, 1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 140.5, 135.5, 132.4, 130.7, 130.5,
128.9, 128.9, 128.6, 128.5, 127.9, 127.3, 126.4, 125.7, 122.9, 121.7,
111.3.
HRMS (ESI): m/z [M + H]+ calcd for C17H10N4: 271.0978; found:
271.0969.
HRMS (ESI): m/z [M + H]+ calcd for C18H11N3: 270.1025; found:
270.1023.
10-(Thiophen-2-yl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2q)
Yellow solid; yield: 78% (86 mg).
10-(4-Fluorophenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2k)
1H NMR (400 MHz, CDCl3):  = 7.92 (d, J = 7.0 Hz, 1 H), 7.85 (d, J = 7.2
Hz, 1 H), 7.77 (d, J = 8.3 Hz, 1 H), 7.73 (d, J = 8.3 Hz, 1 H), 7.67 (d, J = 3.6
Hz, 1 H), 7.60–7.54 (m, 2 H), 7.43 (d, J = 5.0 Hz, 1 H), 7.21 (t, J = 4.4 Hz,
1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 135.1, 134.3, 132.8, 132.1, 130.5,
128.9, 128.3, 127.8, 127.2, 125.7, 125.5, 125.1, 122.2, 121.8, 111.4.
Greenish solid; yield: 81% (93 mg).
1H NMR (400 MHz, CDCl3):  = 8.09–8.02 (m, 2 H), 7.95 (t, J = 6.8 Hz, 2
H), 7.88 (d, J = 8.3 Hz, 1 H), 7.82 (d, J = 8.3 Hz, 1 H), 7.71–7.61 (m, 2 H),
7.29–7.20 (m, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 162.6 (1JC-F = 247.0 Hz), 139.5,
135.2, 132.3, 130.6, 128.8, 128.5, 128.1 (3JC-F = 8.0 Hz), 127.9, 127.4,
126.7 (4JC-F = 3.0 Hz), 125.8, 122.7, 121.4, 115.9 (2JC-F = 22.0 Hz), 111.3.
HRMS (ESI): m/z [M + H]+ calcd for C16H9N3S: 276.0590; found:
276.0587.
HRMS (ESI): m/z [M + H]+ calcd for C18H10FN3: 288.0932; found:
288.0924.
10-(Naphthalen-2-yl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2r)
Yellow solid; yield: 82% (105 mg).
10-(4-Chlorophenyl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2l)
1H NMR (400 MHz, CDCl3):  = 8.51 (d, J = 1.7 Hz, 1 H), 8.19 (dd, J = 8.5,
1.7 Hz, 1 H), 8.08 (d, J = 7.0 Hz, 1 H), 8.02–7.92 (m, 3 H), 7.91–7.85 (m,
2 H), 7.83–7.79 (m, 1 H), 7.72–7.60 (m, 2 H), 7.56–7.51 (m, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 140.6, 135.8, 133.3, 133.1, 132.4,
130.7, 128.9, 128.7, 128.6, 128.1, 127.9, 127.9, 127.7, 127.4, 126.5,
126.3, 125.8, 125.5, 124.2, 123.0, 121.7, 111.4.
Greenish solid; yield: 84% (102 mg).
1H NMR (400 MHz, CDCl3):  = 8.02–7.96 (m, 2 H), 7.95–7.93 (m, 2 H),
7.88 (d, J = 8.3 Hz, 1 H), 7.82 (d, J = 8.3 Hz, 1 H), 7.70–7.61 (m, 2 H),
7.54–7.48 (m, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 139.4, 135.6, 134.2, 132.3, 130.7,
129.1, 129.0, 128.9, 128.6, 128.0, 127.6, 127.5, 125.9, 122.7, 121.7,
111.5.
HRMS (ESI): m/z [M + H]+ calcd for C22H13N3: 320.1182; found:
320.1180.
HRMS (ESI): m/z [M + H]+ calcd for C18H10ClN3: 304.0636; found:
304.0630.
10-Butylbenzo[cd][1,2,3]triazolo[1,5-a]indole (2s)
Dark brown solid; yield: 73% (73 mg).
10-(4-(Trifluoromethyl)phenyl)benzo[cd][1,2,3]triazolo[1,5-a]-
1H NMR (400 MHz, CDCl3):  = 7.88 (d, J = 7.2 Hz, 1 H), 7.81 (d, J = 8.3
Hz, 1 H), 7.77 (d, J = 8.3 Hz, 1 H), 7.72 (d, J = 7.0 Hz, 1 H), 7.66–7.57 (m,
2 H), 3.02 (t, J = 7.6 Hz, 2 H), 1.92–1.85 (m, 2 H), 1.56–1.42 (m, 2 H),
0.99 (t, J = 7.4 Hz, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 141.2, 136.8, 132.8, 130.7, 128.9,
128.7, 127.8, 126.5, 125.4, 123.3, 121.1, 110.9, 30.9, 25.7, 22.3, 13.7.
indole (2ad)
Off-white solid; yield: 92% (125 mg).
1H NMR (400 MHz, CDCl3):  = 8.20–8.13 (m, 2 H), 7.99 (d, J = 7.1 Hz, 1
H), 7.95 (d, J = 7.2 Hz, 1 H), 7.91 (d, J = 8.3 Hz, 1 H), 7.84–7.79 (m, 3 H),
7.73–7.61 (m, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 138.0, 136.2, 134.0, 132.2, 130.7,
130.1 (2JC-F = 33.0 Hz), 129.0, 128.5, 128.0, 127.9, 126.5, 126.1, 125.8
(3JC-F = 4.0 Hz), 123.9 (1JC-F = 270.0 Hz), 122.5, 122.0, 111.7.
HRMS (ESI): m/z [M + H]+ calcd for C16H15N3: 250.1339; found:
250.1334.
HRMS (ESI): m/z [M + H]+ calcd for C19H10F3N3: 338.0900; found:
338.0894.
10-Pentylbenzo[cd][1,2,3]triazolo[1,5-a]indole (2t)
Dark brown solid; yield: 76% (80 mg).
1H NMR (400 MHz, CDCl3):  = 7.90 (d, J = 7.2 Hz, 1 H), 7.83 (d, J = 8.3
Hz, 1 H), 7.79 (d, J = 8.3 Hz, 1 H), 7.73 (d, J = 6.9 Hz, 1 H), 7.63 (q, J = 7.9
Hz, 2 H), 3.02 (t, J = 7.6 Hz, 2 H), 1.96–1.85 (m, 2 H), 1.50–1.35 (m, 4
H), 0.91 (t, J = 7.0 Hz, 3 H).
13C{1H} NMR (101 MHz, CDCl3):  = 141.3, 136.8, 132.9, 130.7, 128.9,
128.7, 127.9, 126.5, 125.5, 123.3, 121.1, 111.0, 31.4, 28.5, 26.0, 22.3,
13.9.
10-(Pyridin-3-yl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2p)
Brown solid; yield: 83% (89 mg).
1H NMR (400 MHz, CDCl3):  = 9.27 (d, J = 2.3 Hz, 1 H), 8.72–8.60 (m, 1
H), 8.43–8.40 (m, 1 H), 8.00 (d, J = 7.1 Hz, 1 H), 7.95 (d, J = 7.3 Hz, 1 H),
7.88 (d, J = 8.3 Hz, 1 H), 7.82 (d, J = 8.3 Hz, 1 H), 7.71–7.59 (m, 2 H),
7.54–7.45 (m, 1 H).
13C{1H} NMR (101 MHz, CDCl3):  = 149.4, 147.5, 137.1, 136.0, 133.5,
132.2, 130.7, 129.0, 128.5, 128.0, 127.8, 126.8, 126.1, 123.8, 122.4,
122.0, 111.7.
HRMS (ESI): m/z [M + H]+ calcd for C17H17N3: 264.1495; found:
264.1462.
HRMS (ESI): m/z [M + H]+ calcd for C17H10N4: 271.0978; found:
271.0974.
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–K

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K. Majeed et al.
Paper
Synthesis
10-(Thiophen-3-yl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2af)
References
Yellow solid; yield: 87% (95 mg).
1H NMR (400 MHz, CDCl3):  = 7.93–7.87 (m, 3 H), 7.83 (d, J = 8.3 Hz, 1
H), 7.80–7.74 (m, 2 H), 7.66–7.58 (m, 2 H), 7.51 (dd, J = 5.0, 2.9 Hz, 1
H).
13C{1H} NMR (101 MHz, CDCl3):  = 136.4, 134.9, 132.4, 131.7, 130.7,
128.9, 128.6, 127.9, 127.2, 126.5, 126.1, 125.7, 122.7, 122.5, 121.4,
111.4.
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6961. (e) Leeson, P. D.; Springthorpe, B. Nat. Rev. Drug Discovery
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413. (b) Lipshutz, B. H. Chem. Rev. 1986, 86, 795. (c) Shipman, M.
Contemp. Org. Synth. 1995, 2, 1.
HRMS (ESI): m/z [M + H]+ calcd for C16H9N3S: 276.0590; found:
276.0584.
10-(Naphthalen-2-yl)benzo[cd][1,2,3]triazolo[1,5-a]indole (2r)
(3) (a) Varney, M. D.; Marzoni, G. P.; Palmer, C. L.; Deal, J. G.;
Webber, S.; Welsh, K. M.; Bacquet, R. J.; Bartlett, C. A.; Morse, C.
A. J. Med. Chem. 1992, 35, 663. (b) López-Rodríguez, M. L.;
Porras, E.; Morcillo, M. J.; Benhamú, B.; Soto, L. J.; Lavandera, J.
L.; Ramos, J. A.; Olivella, M.; Campillo, M.; Pardo, L. J. Med. Chem.
2003, 46, 5638. (c) Yin, H.; Xu, Y.; Qian, X. Bioorg. Med. Chem.
2007, 15, 1356. (d) Xue, X.; Zhang, Y.; Liu, Z.; Song, M.; Xing, Y.;
Xiang, Q.; Wang, Z.; Tu, Z.; Zhou, Y.; Ding, K.; Xu, Y. J. Med. Chem.
2016, 59, 1565. (e) Yan, M.; Zhao, J.; Sun, D.; Sun, W.; Zhang, B.;
Deng, W.; Zhang, D.; Wang, L. Tetrahedron 2017, 73, 3355.
(4) (a) Appelt, K.; Bacquet, R. J.; Bartlett, C. A.; Booth, C. L. J.; Freer,
S. T.; Fuhry, M. A. M.; Gehring, M. R.; Herrmann, S. M.; Howland,
E. F. J. Med. Chem. 1991, 34, 1925. (b) Kamal, A.; Ramakrishna,
G.; Nayak, V. L.; Raju, P.; Rao, A. V. S.; Viswanath, A.;
Vishnuvardhan, M. V. P. S.; Ramakrishna, S.; Srinivas, G. Bioorg.
Med. Chem. 2012, 20, 789. (c) Sinha, S. H.; Owens, E. A.; Feng, Y.;
Yang, Y.; Xie, Y.; Tu, Y.; Henary, M.; Zheng, Y. G. Eur. J. Med.
Chem. 2012, 54, 647. (d) Lee, H.; Berezin, M. Y.; Henary, M.;
Strekowski, L.; Achilefu, S. J. Photochem. Photobiol., A 2008, 200,
438.
Greenish solid; yield: 80% (102 mg).
1H NMR (400 MHz, CDCl3):  = 8.51 (d, J = 1.7 Hz, 1 H), 8.19 (dd, J = 8.4,
1.6 Hz, 1 H), 8.08 (d, J = 7.2 Hz, 1 H), 8.02–7.92 (m, 3 H), 7.91–7.85 (m,
2 H), 7.83–7.79 (m, 1 H), 7.72–7.60 (m, 2 H), 7.57–7.49 (m, 2 H).
13C{1H} NMR (101 MHz, CDCl3):  = 140.5, 135.6, 133.3, 133.1, 132.2,
130.6, 128.8, 128.5, 128.5, 128.1, 127.8, 127.6, 127.3, 126.4, 126.3,
125.7, 125.4, 124.1, 122.8, 121.6, 111.3.
HRMS (ESI): m/z [M + H]+ calcd for C22H13N3: 320.1182; found:
320.1178.
Funding Information
The authors are grateful for the support and funding from the Nation-
al Natural Science Foundation of China (No. 21702165 and No.
51673156) and the Natural Science Foundation of Shaanxi Province
(No. 2018JQ2018). Supported by the Fundamental Research Funds for
the Central Universities (No. 3102017jc01001).NationalNaturalScience
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Supporting Information
Supporting information for this article is available online at
https://doi.org/10.1055/a-1364-9308.
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(6) Majeed, K.; Wang, L.; Liu, B.; Guo, Z.; Zhou, F.; Zhang, Q. J. Org.
Chem. 2021, 86, 207.
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© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–K